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Hematite(α-Fe_2O_3)has been extensively studied as a promising photocatalyst,with the capacity to split water under visible light.To tune its electronic structure and improve the performance for oxygen evolution reaction(OER),high-quality single crystals ofα-Fe_2O_3nanoparticles were synthesized and doped by various transition metals(M=V,Cr,Mn,Zn,Co,Ni,Cu,Nb,Mo,Ti)by a molten-salt flux method.Optical,electronic and catalytic properties of transition-metal-dopedα-Fe_2O_3(TM-dopedα-Fe_2O_3)have been systematically investigated.Cobalt has been identified as the best dopant forα-Fe_2O_3,reducing the OER overpotential by 0.16 V with respect to the undoped. 相似文献
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面对日益严峻的环境问题,我国提出了“碳中和、碳达峰”的宏伟目标,清洁能源是实现双碳目标的有效手段之一。电解水制氢是一种制备清洁能源的重要方法,然而,电解水过程中析氧反应的缓慢动力学和较高过电位是妨碍水裂解效率的关键因素。金属–有机骨架材料（metal-organic framework,MOF）由于其规整的微观结构、较大的比表面积和可调的孔径等优点,被认为是电解水制氢的优异催化剂。综述了MOF材料用于催化析氧反应的最新研究进展,分析了该类材料的设计策略和催化机制。系统归纳了MOF基催化剂的各种调制策略,包括结晶度调制、电子调制、缺陷调制以及形态调制,并且对MOF材料作为析氧反应催化剂面临的挑战和机遇做出了展望。 相似文献
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Yao Pang Shengli Zhu Zhenduo Cui Yanqin Liang Zhaoyang Li Shuilin Wu 《自然科学进展(英文版)》2021,31(2):201-206
Hydrogen evolution reaction(HER) through electrocatalysis using cost-efficient and long-term stable bimetallic phosphide as electrocatalyst holds a great promise for sustainable clean energy technologies. In this study, self-supported nanoporous Ni-Co-P(np-Ni-Co-P) catalyst with amorphous structure was synthesized by utilizing a facile electrochemical dealloying strategy. The results showed that due to the nanoporous structure, disorder atomic arrangement and alloying effect, the np-Ni-Co-P exhi... 相似文献
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A comparison of structural and magnetic properties of as-prepared and annealed(900 1C) Mg doped Zn ferrite nanoparticles(Zn1 xMgxFe2O4,with x=0, 0.1, 0.2, 0.3, 0.4 and 0.5) is presented. X-ray diffraction(XRD) studies confirmed the cubic spinel structure for both the as-prepared and annealed nanoparticles. The average crystallite size and lattice parameter were increased by annealing. Scanning electron microscopy(SEM)images also showed that the average particle size increased after annealing. Fourier transform infrared spectroscopy(FTIR) also confirmed the spinel structure for both series of nanoparticles. For both annealed and as-prepared nanoparticles, the O–Mtet.–O vibrational band shifts towards higher wave numbers with increased Mg concentration due to cationic rearrangement on the lattice sites. Magnetization studies revealed an anomalous decreasing magnetization for the annealed nanoparticles which is also ascribed to cationic rearrangement on the lattice sites after annealing. The measurement of coercivity showed a decreasing trend by annealing due to the increased nanoparticle size and better crystallinity. 相似文献
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The water electrolysis for hydrogen production is constrained by the thermodynamically unfavorable oxygen evolution reaction(OER),which requires input of a large amount of energy to drive the reaction.One of the key challenges to increase the efficiency of the water electrolysis system is to develop highly effective and robust electrocatalysts for the OER.In the past 20–30 years,significant progresses have been made in the development of efficient electrocatalysts,including metal oxides,metal oxide-carbon nanotubes(CNTs) hybrid and metal-free CNTs based materials for the OER.In this critical review,the overall progress of metal oxides catalysts and the role of CNTs in the development of OER catalyst are summarized,and the latest development of new metal free CNTs-based OER catalyst is discussed. 相似文献
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《自然科学进展(英文版)》2020,30(2):160-167
Atrazine(ATZ) is a known herbicide used in agriculture and caused many concerns according to its toxicity.Herein,we have prepared NiCo_2 O_4 nanorods that can work as a photocatalyst under visible light exposure by Ag loading through a simple route.The characterizations revealed the role of Ag for improving the structural,optical and optoelectronic properties of the produced photocatalyst.The Ag loading with 5 wt% confirms the minimization of the bandgap from 3.6 down to 2.57 eV with enhanced visible light absorption and sustaining the magnetic properties.The Ag/NiCo_2 O_4 nanorods showed a superior photodegradation of ATZ within 20 min at2.0 g L~(-1) with excellent recyclability.The enhancement of the photocatalytic activity is referred to the local surface plasmon resonance of Ag-loaded photocatalyst.This reduces the electron-hole recombination and outperforms the unloaded sample.This work is highlighting the application of magnetically separable spinel photocatalysts for the removal of herbicides and water remediation. 相似文献
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《自然科学进展(英文版)》2022,32(6):705-714
Designing advanced electrocatalysts for the oxygen evolution reaction (OER) is of great significance owing to its crucial role in facilitating the production of clean hydrogen energy via water splitting. To date, it has been widely accepted that a pre-oxidation process with the in-situ generation of the catalytically active high-valence metal sites is essential for promoting the OER behavior of most transition-metal-based OER catalysts, or more felicitously speaking, pre-catalysts. Hence, exploring such pre-catalysts with high pre-oxidation reactivity is of high promise. Herein, we proposed the dual elemental modulation in the cationic and anionic sites of the multi-metal Prussian blue analogue (PBA) pre-catalysts, resulting in promoted OER behavior benefitted from the efficient pre-oxidation ability as well as the multi-metal synergy. Detailed investigations indicate that the Co-containing multi-metallic cations and mixed FeIIICoIII cyanide anions in NiCuCoII–FeIIICoIII PBA (denoted as NiCuCoII–FeIIICoIII) are beneficial to OER catalysis owing to the high intrinsic activity guaranteed by the local Co3+ active sites as well as the optimal multi-metal synergy. After the facile pre-oxidation process, additional high-valence Ni, Cu and Fe ions can be in-situ formed and serve as the active sites, thereby resulting in significantly improved OER behavior. For example, the OER current density of NiCuCoII–FeIIICoIII exhibits 1.81 times enhancement even after 72 ?h continuous OER catalysis, and the required overpotential for 10 ?mA ?cm?2 reduces from 288 ?mV for the fresh pre-catalyst to a remarkable record of 251 ?mV after the pre-oxidation-induced activation, making the optimal PBA-based catalyst a promising candidate for efficient and durable water electrolysis. 相似文献
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以金属有机骨架(metal-organic frameworks, MOFs)化合物为前驱体, 通过退火、硫化等后续处理方法成功制备了由 NiFe2O4 纳米棒与 Co9S8 空心球组装而成的杂化纳米结构. 该复合催化剂因具有较大的比表面积以及各组分间强力的协同作用, 在电催化析氧反应(oxygen evolution reaction, OER)中表现出了优异的催化活性. 在 1 mol/L KOH 电解质中, 当电流密度达到 10 mA/cm2 时, 仅需 290 mV 的过电位, 且 Tafel 斜率仅为 63.02 mV/dec. 此外, 1 000 次循环伏安(cyclic voltammetry, CV)测试后仍然具有良好的催化活性, 表明该复合催化剂具有优异的稳定性. 研究成果不仅为设计廉价、高效且稳定的析氧催化剂提供了设计思路, 也为其他新型纳米复合材料的合成和应用奠定了基础. 相似文献
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用MD方法计算磁场条件下水的表面张力系数 总被引：2，自引：0，他引：2
本文采用分子动力学模拟（Molecular Dynamics simulation简称MD）方法对不同磁场和温度条件下水体系的表面张力系数进行了计算。结果表明水的表面张力系数和磁感应强度之间具有多极值关系,特别在常温下以及磁感应强度为0.25T时,磁场对水体表面张力系数的影响最为明显。通过对径向分布函数的计算发现,磁场可以影响g(r)的分布,使水的结构发生变化,从而导致水的表面张力系数发生改变。 相似文献
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A noble-metal-free heterostructure composed of Ta_3N_5 nanosheets and MoS_2 co-catalyst was developed as an efficient photocatalyst for hydrogen production. In special, the MoS_2/Ta_3N_5 heterostructure with 5.2 wt% of MoS_2 exhibits a H_2 generation rate of 119.4 μmol h~(-1) g-1, which is comparable to that of Ta_3N_5 nanosheets with Pt as co-catalyst. The efficient H2 generation for MoS_2/Ta3N5 heterostructure is resulted from the short diffusion distance of photo-excited charge carriers in Ta3 N5 nanosheets, efficient transfer of electrons from Ta3 N5 nanosheets to MoS_2 surface, and reduced overpotential for water reduction. Furthermore, the stability of the MoS_2/Ta_3N_5 heterostructured photocatalysts are evaluated for the photocatalytic H_2 generation. 相似文献
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本文研究了钌镍氧化物阴极的制备工艺条件对电性能的影响，以及钌镍氧化物活性阴极在碱溶液中的析氢反应，测定了阴极析氢反应的动力学参数，提出了合理的阴极析氢反应机理。最后，研究了钌镍氧化物活性阴极的失活和修复。 相似文献
14.
NO及其生成调节与运动 总被引：3，自引：0，他引：3
一氧化氮作为重要的细胞信使和效应分子,具有广泛的生物学效应,在介绍NO的生理功能基础之上,阐述了NO的调节机制以及运动对NO的影响,最后展望了NO在运动医学领域中的应用前景,并对今后的研究方向提出一些建议. 相似文献
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本文提出的对偶原则就是以 Q 和 QV 分别作为电场量和磁场量的基本对偶元素.就是在电场量和磁场量的因次公式中,分别令 Q 和 QV 所代表的基本量为零因次,如果两个量的因次式变成相同,则它们可以对偶.运用这个原则,可以从电场的关系或方程得到对偶的磁场的关系或方程.或者,反过来,本文限于静电场和稳恒磁场. 相似文献
16.
王积成 《汕头大学学报(自然科学版)》1987,(1)
我们在电场和磁场中的对偶原则一文中,已经提出,Q和QV是这两种场的基本对偶元素.并提出,如果有两个不同场的量可以构成对偶对,则它们分别所属的因次式,在假定Q和QV为零因次时,应该相同.本文将进一步从这两种场的不同方面,证明这个原则的正确性,并介绍运用这个原则的方法问题. 相似文献
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单组分单相不发生化学变化的系统,自由度为2,如要考虑磁场,则自由度为3.本文基于温度、压力和磁场三个独立强度性质,合理地给出磁场下平衡过程的热力学的基本方程组.本文计算了在磁场为1万高斯和温度在253,273,293和313K时核磁子17 O,33S和77Se的磁极化M和磁性热力学函数. 相似文献
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陈松良 《渤海大学学报(自然科学版)》2002,23(1):65-66
设 p是素数 ,n是正整数 ,Fp =Z/(p) ,a,b∈ Fp,用初等方法给出了 Fp 上形加 xpn +ax +b或 xpn +axpn-1+b的多项式不可约的一个充要条件 相似文献
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黄天培 《四川大学学报(自然科学版)》1990,27(2):121-129
利用分圆域Q(ζ)的根式扩张,对有理数域的(奇素数)p次循环扩张进行了研究,得到了任意p次循环扩张的定义方程.文[1],[2]在p=3时已有了很好的结果;本文讨论了p=5的情形,最后得到一类由含一个有理参数的五次方程确定的五次循环扩张. 相似文献
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